Method and means for rewinding pressure-sensitive sheet material



March 31, 1970 L. J. CASEY 3,503,567

METHOD AND MEANS FOR REWINDING PRESSURE-SENSITIVE SHEET MATERIAL Filed Nov. 20, 196'? 2 Sheets-Sheet l H YDMUUC PRESSURE PISTON SYSTEM FIG. 1-

IN VEN TOR Zawrence .Case y y March 31, 1910 L. J. CASEY 3,503, 7

METHOD AND MEANS FOR REWINDING PRESSURE-SENSITIVE SHEET MATERIAL Filed Nov. 20, 196'? 2 Sheets-Sheet 2 United States Patent 3,503,567 METHOD AND MEANS FOR REWINDING PRES- SURE-SENSITIVE SHEET MATERIAL Lawrence J. Casey, Appleton, Wis., assignor to Appleton,

Coated Paper Company, Appleton, Wis., a corporation of Wisconsin Filed Nov. 20, 1967, Ser. No. 684,195 Int. Cl. B65h 17/02 US. Cl. 24267.1 12 Claims ABSTRACT OF THE DISCLOSURE Sheet material such as a base paper having a pressuresensitive coating containing a multiplicity of capsules which emit a dye solution when fractured, is rewound from a parent roll onto a plurality of finished-product rolls suitable for marketing. To meet marketing requirements that said rolls should have substantially uniform hardness throughout the roll and along the axial length of the roll, the invention provides a re-winding mechanism which includes a Winding drum which is in pressure engagement with the finished-product rolls. The sheel material is passed between said rolls and the winding drum, whereupon the rolls and drum exert a nipping action on the sheet which is beneficial in producing the desired roll hardness. A cushion surface on the winding drum absorbs suflicient of the engagement pressure between the rolls and drum to protect the pressure-sensitive capsules of the sheet while maintaining the said nipping action.

This invention relates to methods and means for the manufacture of rolls of pressure-sensitive material such as paper coated or impregnated with an emulsion containing encapsulated color-containing liquids. Such materials have various uses and applications, one of the most popular of which is reproduction paper of the type marketed by the National Cash Register Company of Dayton, Ohio, under the trade name NCR Paper. This paper is useful in making copies similar to the familiar carbon copies, except that the process is clean, for under the impact of typewriter type faces, or the pressure of a pencil or pen, capsules are broken to release colorcontaining constituents which combine with other components of the paper faithfully to reproduce the letter or other symbol represented by the type face or pen impresslon.

In the manufacture of such pressure-sensitive material, the paper is emulsion-coated and dried in apparatus, such as disclosed in the Busch et al. Patent No. 3,311,499. The end product is a roll of paper having a very substantial width or axial length. Subsequently, the paper is cut and re-rolled to customers specifications. Market conditions require that such final-product rolls be solid and dense, or, as called in the trade, hard, and that the crosssection or profile of the rolls should be as nearly circular as reasonably practicable.

In the re-Winding of ordinary papers, the desired hardness and profile can be obtained by conventional equipment in which the sheet is passed between a hard-surfaced winding drum and one or more finished-product rolls which exert pressure thereagainst; the nip action exerted on the sheet by such pressure relationships provides the restraint necessary to produce rolls having the desired qualities. With pressure-sensitive sheets, however, the nipping action against a hard-surfaced winding roll causes fracture of capsules with corresponding development of color.

In an effort to eliminate fracturing of the capsules or other damage to the emulsion coating of pressure-sensitive sheets, conventional re-winding equipment was modified so that the winding drum was no longer engaged by the finished-product rolls. In this arrangement, it was found that hardness control of the finished rolls became primarily a function of the torque provided by the hydraulic drive of the shafts on which the finished-product rolls are Wound, and the slippage of the paper coils on said shafts. These two factors combined to produce a web tension which was the primary factor in the control of roll hardness. However, the tension required for hardness uniformity varied with the width of the rolls such that with the same machine softness increased with roll width. As .noted above, in the conventional roll-winding equipment, the nip action between the finished-product rolls Was a prime factor in producing finished rolls of uniform hardness and profile. In the absence of the nip action of a winding drum, the finished-product roll were characterized by lack of uniformity, as respects hardness, across the Width of a finished roll.

I have found that a winding drum can be used to provide the desired nip action for producing product rolls of excellent hardness characteristic and desired profile when the winding drum is provided with a peripheral surface which is characterized to provide cushioning means, whereby the net pressure and nipping action exerted by the finished rolls against the winding drum may be maintained below the threshold level of fracture, or preferably below about ten pounds per square inch. In a preferred form of practicing the invention, I provide the winding drum With a relatively thin coating of resilient material such as sponge rubber or a foamed synthetic material, as presently more specifically described.

It is therefore an object of my invention to provide a method and means for re-winding a parent roll of pressure-sensitive material into finished-product rolls having desired uniform hardness and profile without damage to the pressure-sensitive components of said material.

It is another object of my invention to provide a rewinding method and means for pressure-sensitive material, whereby desired uniform hardness and profile may be obtained in each of a plurality of finished-product rolls wound on a common shaft, regardless of the Width of the individual rolls.

These and other objects and advantages of the invention will hereinafter appear and, for purpose of illustration, but not of limitation, an embodiment of the invention is shown in the accompanying drawing, in which:

FIG. 1 is a schematic representation of roll-winding equipment which is conventional in all respects except for the winding drum which has been reconstructed pursuant to the invention;

FIG. 2 is a cross-sectional representation showing the nip action applied to the material as it passes between the winding drum and is wound to form a finished roll of material; and

FIGS. 3 and 4 are fragmentary elevational views of winding drums, showing alternative methods of applying the cushioning material thereto.

Referring now to FIG. 1, the schematically illustrated roll-winding machine is of conventional design well known to workers in the art. The parent roll 1 of the material to be re-wound is on a shaft journalled in appropriate supports 2, and to exert a restraint on the free rotation of the roll shaft in its bearings, braking action is applied thereto. There is schematically shown a brake shoe 3 carried by the pivotally mounted arm 4 which is drawn into counterclockwise rotation by hydraulic or air pressure Within the cylinder 5. The sheet W of the material being re-wound is of the type referred to as pressure-sensitive such as formed of a paper base sheet 6 having a coating of encapsulated color-forming liquid as previously described.

At the dancer roll section 7, the material passes about an idler roll 8, a dancer roll 9, which acts as a damper to reduce tension surges which may be caused by an outof-round parent roll 1, and then about idler roll 10, from which it progresses to the slitting and re-wind section 11. At station 11, the web passes about a bowed expander roll 12 which spreads the material to eliminate wrinkles, an idler 14, and then between the anvil roll 15 and the slitters 16. The slit webs then pass about idler 17, holdback roll 18 and winding drum 19, to the re-wind shafts, for re-winding into the finished-product rolls schematically illustrated at 20 and 21, FIG. 1. The respective re-wind shafts are driven by a conventional hydraulic drive means, well known to the art and therefore schematically illustrated in the drawing. It is common in the art to provide a hydraulic pressure piston system whereby the re-wind shafts may be given any desired down thrust, ranging from a condition in which the down thrust is represented solely by the weight of the shafts, accessory equipment, and the developing paper rolls thereon, to any desired amount of additional loading bias applied thereto.

As indicated in FIG. 2, the tubular cores 22 of the developing finished product roll 20 are mounted on the re-wind shaft 24 and held in the desired spaced relation by slip rings 23 keyed to the shaft. This, also, is common practice. The re-wind shafts are the primary driving elements of the mechanism, and it is the usual and advantageous practive to drive the respective re-wind shafts at a speed faster than necessary to achieve the desired lineal speed of travel of the sheet or web as it leaves the parent roll. In practicing the present invention, I have achieved excellent results with a web speed travel of one thousand feet per minute, and an overspeed on the re-wind shafts of 10%. In use, one of the webs of the slit sheet leaves re-wind drum 19 and passes on to the roll core for the finished product roll 20, the adjacent one passes to that for roll 21, and this alternate winding relationship follows until the several webs of the slit sheet are all accommodated.

The purpose of the hold-back roll 18 is to keep the several webs taut between said roll and the winding drum 19. This is accomplished by having the peripheral speed of roll 18 very slightly slower than the web speed. The winding drum is given the same peripheral speed as that of roll 18, and, assuming a common drive such as motor 25 and a difference in diameters of roll 18 and drum 19, the drive mechanism may advantageously include a suitable gear box 26.

The re-wind drum 19, FIG. 2, is of conventional metal construction, in which a hub or series of hubs 28 are keyed to shaft 27 and webs 29 carry the cylindrical wall 30. Pursuant to my invention, however, the drum 19 is cushioned, to partly absorb the pressure exerted thereon by the respective re-wind shafts and the finished-product rolls developing thereon. Advantageously, and as illustrated, the cushioning of the drum 19 may be accomplished by applying a layer 31 of sponge rubber or foamed synthetic material to the drum; the layer 31 may be applied to the drum by any suitable adhesive. The layer 31 is rather thin in relation to the drum diameter, such as a ratio of layer thickness to drum diameter of 1 to 20-50, but it is seldom necessary to exceed a thicknes of one inch independent of the roll diameter. A suitable combination makes use of a drum having a diameter of 9.25 inches and a resilient layer of inch.

I have found that the density or hardness of the rubber should be in the range of from 8 to 12 on the Shore durometer scale, with a hardness of 10 producing excellent results with the NCR paper. It is preferable that the outer surface of the cushioning material be reasonably free of voids or pits, although this does not appear to be critical. The cushioning layer may be in the form of a continuous layer having a fiat surface, as suggested in FIG, 3, or arranged on the drum with a surface formed with a geometrical pattern of individual cushions, such as the diamond-shaped blocks 31a of FIG. 4. Such a pattern provides air-flow channels 31b along which air may escape as the cushion is compressed. As shown in FIG. 2, the emulsion layer is on the side of the sheet opposite the cushion surface of the winding drum.

As indicated in FIG. 2, the windup shaft 24 (and the shaft for the roll 21 as well) is driven in clockwise direction and the shaft 27 of the winding drum 19, in counterclockwise direction. As the web enters between the winding drum and the respective finished-product rolls 20 and 21, the web is nipped therebetween. The resilient facing of the winding drum compresses under the load, absorbing enough of the pressure to prevent fracture of the dye-containing capsules, While maintaining a desired hardness and uniform profile of the respective rolls 20 and 21.

In a typical re-wind operation in which the web speed was of the order of 800 feet per minute and the hydraulic pressure piston system on the winding shafts was adjusted so that the loading or pressure exerted against the winding drum was represented only by the weight of the winding shaft assemblies, the following hardness figures were found in a quality control audit of 23-inch wide, 2l-inch diameter, roll of NCR paper:

Left end of roll Test position Center of roll Left end of roll Test position Right end of roll Center of roll The substantial uniformity of hardness throughout rolls of substantially different width was obtained with almost complete freedom from handling smudge. The auditor appraised the rolls as being of excellent quality.

While this invention has been described in preferred form, it is to be understood that modifications thereof may be made without departure from the ambit of the invention.

I claim:

1. The method of re-winding a strip of material having pressure-sensitive elements incorporated therein from a parent roll onto one or more finished-product rolls, which includes the steps of drawing said strip from said parent roll, passing said strip through guiding and tensioning means to effect desired conditions of tension and linear speed thereof, passing said strip between a winding drum in pressure engagement with said one or more finishedproduct rolls to cause said strip to wind on said rolls while exerting a nipping action on said strip by reason of said pressure engagement, and cushioning said strip during said nipping action to minimize damage to said pressure-sensitive elements.

2. The method recited in claim 1, in which the cushioning step is a function of the winding drum.

3. The method recited in claim 1, in which the pressure-sensitive elements of the material face in the direction away from the winding drum.

4. The method recited in claim 1, in which the finishedproduet rolls exert a downward pressure on said winding drum.

5. Mechanism for re-Winding pressure-sensitive sheet material from a parent roll onto one or more finishedproduct rolls, comprising, in combination,

means for mounting said parent roll for rotation,

means for rotating said finished-product rolls to withdraw said sheet from said parent roll,

sheet-guiding and tensioning means interposed between said parent rolls and said finished-product rolls,

a winding drurn having a continuous peripheral surface mounted for rotation in pressure contact with the respective finished-product rolls, said winding drum receiving said sheet from said guiding and tensioning means and nipping said sheet against said finishedproduct rolls, and

a cushioning layer on the peripheral surface of said winding drum for pressure contact with said finishedproduct rolls to absorb a portion of the contact pressure therebetween.

6. Mechanism according to claim 5, in which the cushioning means comprises a body of soft, rubber-like material.

7. Mechanism according to claim 5 in which the cushion layer on the winding drum has a continuous even surface.

8. Mechanism according to claim 5 in which the cushion layer on the winding drum has an interrupted surface to provide a plurality of air-distribution passages.

" 9, Mechanism according to claim in which the thiclrness of said layer is to the diameter of said winding drum.

10. Mechanism according to claim 5 in which the hardness of said cushion layer is within a Shore durometer range of from 8 to 12. 11. Mechanism according to claim 5 in which the guidmg and tensioning means includes a hold-back roll immediately ahead of said winding drum, and means for driving said hold-back roll at less peripheral speed than the lineal speed of said sheet.

12. Mechanism according to claim 11 in which the hold-back roll and the winding drum are driven at substantially the same peripheral speed.

References Cited UNITED STATES PATENTS 2,702,772 2/ 1955 Pronio 156184 3,377,033 4/1968 Link 24256.2 2,438,296 3/1948 Nassimbene 242 X 2,985,398 5/1961 Rockstrom et al. 24265 3,222,004 12/1965 CroWe 242569 3,394,897 7/1968 Martin 24266 3,412,950 11/ 1968 Martin 24254 LEONARD D. CHRISTIAN, Primary Examiner Cl.X.R, .4%"6? I 

